Transfer printing sheet with impregnating agents and two-component electrophotographic toner and transfer printing of textile materials of cotton

Abstract

The transfer sheet or web is intended for the use in a heat transfer printing process of cotton, of cotton-polyester blend or of nitrogen containing textile fibers such as wool, silk or nylon. It comprises on its surface at least one organic impregnating agent which has a melting point between 60° and 230° C. and is no polymer, at least one water insoluble, non-subliming dyestuff, and the minimum amount of a binder. The dyestuff forms a pattern or image which is heat contact printed on said textile substrate without the use of carrier vapors or vacuum. The pattern to be heat transferred may also be prepared in an electrophotographic process using a new toner comprising particles of impregnating agent, binder and dyestuff. The pattern on the transfer support is transferred at a temperature between 160° and 230° C. during 30 to 60 seconds to said textile substrate. The printings obtained have very good light, rubbing and washing fastnesses; the handling is not impaired.

We claim: 
     
       1. In a process for the preparation of a transfer printing support in sheet or web form for the thermoprinting of hydroxyl group or nitrogen containing textile fiber materials, comprising the steps of: (a) providing an electrophotographic toner of the two-component type by blending finely divided toner particles having a particle size of from 5 to 20 micrometers containing at least one dyestuff and a polymeric binder, with a particulate carrier, the carrier particles being coarser than the toner particles,   (b) providing a latent electrostatic image on a photoconductor surface by electrophotography,   (c) developing said latent electrostatic image of step (b) by means of the toner of step (a),   (d) transferring said developed image of step (c) onto a flat flexible transfer printing substrate, and   (e) fixing said transferred image obtained in step (d) on said transfer printing substrate by at least one means selected from heat and pressure, the improvements comprising:   (1) using dyestuff in step (a) which is not substantially water soluble at leasat at neutral pH, which doess not visibly sublime under the conditions of sublimation transfer printing and which is capable of thermosoling,   (2) using in step (d) a flat flexible transfer printing substrate which has been coated with a mixture of at least one impregnating agent which is a non-toxic organic substance containing at least one nitrogen atom in its molecule, which is solid up to 60° C. and has a melting temperature in the range from 60° C. to 230° C., which is liquid up to at least 230° C. and substantially colorless, and which is not a film-forming polymer wherein the impregnating agent is selected from the group consisting of caprolactam, nicotinic amide, isonicotinic amide, propylene urea, ethylene urea, glyoxal monurein, urea, 5,5-dimethyl hydantoin, imidazol, 2-methyl imidazol, N-methyl pyrrolidone, N-hydroxy succinimide, biuret, dimethylol urea, dimethylol hydroxyethylene urea, dimethylol ethylene urea, and mixtures thereof; and a polymeric binder,   (3) said dyestuff of step (1) and said impregnating agent of step (2) being selected such that the impregnating agent in its liquid state but not in its solid state has solvent properties for said dyestuff.   
     
     
       2. A transfer printing process for printing a cellulose or nitrogen containing textile substrate by means of a transfer printing support obtained by the process of claim 1, characterized by the fact that said textile substrate is surface contacted with said transfer printing support and the composite so formed is heated during 10 to 60 seconds to a temperature in the range of from 160° to 230° C. 
     
     
       3. The process of claim 2 wherein said textile substrate is a cotton fabric. 
     
     
       4. The process of claim 2 wherein said textile substrate is a cotton-polyester blend fabric. 
     
     
       5. The process of claim 2 wherein said textile substrate is a cotton fabric pretreated with an impregnating agent as defined in claim 1 in an amount of 0.5 to 10% by weight of the dry fabric. 
     
     
       6. The process of claim 2 wherein the transfer printing support used contains a water soluble polymer as a binder, and the textile material is rinsed after said transfer printing step with water to remove any water soluble polymer binder which might have been transferred thereto during said transfer step. 
     
     
       7. The process of claim 6, wherein said impregnating agent for pretreatment is applied to said textile material by a heat transfer step wherein a transfer support is used comprising a surface layer of said impregnating agent, and said transfer to the textile material to be pretreated is effected at a temperature between 170° and 200° C. during a time period of 10 to 30 seconds. 
     
     
       8. An electrophotographic toner of the two-component type for the use in the process of claim 2, comprising a blend of finely divided toner particles having a particle size of from 5 to 20 micrometers containing at least one dyestuff as defined in claim 1 and a binder, and a particulate carrier capable of electrostatically charging said finely divided particles, said carrier particles being coarser than said toner particles. 
     
     
       9. The electrophotographic toner of claim 8 in which said finely divided toner particles also comprise an impregnating agent which is a non-toxic organic substance containing at least one nitrogen atom in its molecule, which is solid up to 60° C. and has a melting temperature in the range from 60° C. to 230° C. which is liquid up to at least 230° C. and substantially colorless, which is not a film-forming polymer, and which in its liquid state but not in its solid state has solvent properties for said dyestuff wherein the impregnating agent is selcted from the group consisting of caprolactam, nicotinic amide, isonicotinic amide, propylene urea, ethylene urea, glyoxal monurein, urea, 5,5-dimethyl hydantoin, imidazol, 2-methyl imidazol, N-methyl pyrrolidone, N-hydroxy succinimide, biuret, dimethylol urea, dimethylol hydroxyethylene urea, dimethylol ethylene urea, and mixtures thereof. 
     
     
       10. The electrophotographic toner of claim 9 in which the impregnating agent is urea, 5,5-dimethylhydantoin or nicotonic acid. 
     
     
       11. The electrophotographic toner of claim 10 in which the binder is an acrylic resin having a softening point between about 60° and about 120° C. 
     
     
       12. The electrophotographic toner of claim 11 comprising nicotonic amide, acrylic ester resin, C.I. Disperse Red 346 and iron powder. 
     
     
       13. The process of claim 1 wherein the impregnating agent is urea, 5,5-dimethylhydantoin or nicotinic amide. 
     
     
       14. The process of claim 13 wherein the binder is an acrylic resin having a softening point between 60° and about 120° C. 
     
     
       15. The process of claim 1 wherein said finely divided toner particles comprise C.I. Disperse Blue 329 and n-butyl methacrylate and said particulate carrier is powdered iron.